Empirical antibiotic use is prescribed in managing children with pneumonia worldwide. We assessed the usefulness of procalcitonin (PCT) and interferon-alpha (IFN- α ) in differentiating viral from bacterial pneumonia. Among 159 hospitalized children, pneumonia was diagnosed based on clinical complaints plus pulmonary infi ltrate. Aetiology was investigated for 9 viruses and 4 atypical and 3 typical bacteria. PCT and IFN- α were measured in the serum sample collected on admission. Eight patients had bacteraemic infections, 38 had non-bacteraemic typical infections, and 19 patients had atypical bacterial infections. Viral and unknown aetiology was established in 57 (36%) and 34 (21%) cases, respectively. Three patients with bacterial infection without collected blood culture were excluded. IFN- α (IU/ml) was detectable in 20 (13%) cases. The difference among median PCT values of the bacteraemic (4.22; 1.56 – 7.56), non-bacteraemic typical bacterial (1.47; 0.24 – 4.07), atypical bacterial (0.18; 0.06 – 1.03) and only viral (0.65; 0.11 – 2.22) subgroups was signifi cant ( p 0.02). PCT was 2 ng/ml in 52 (33%) cases. The presence of IFN- α was associated with PCT 2 ng/ml (90% vs. 64%, p 0.02). The negative predictive value (95% confi dence interval) of PCT 2 ng/ml was 95% (89 – 100%), 89% (78 – 100%), 93% (85 – 100%) for differentiation of bacteraemic from viral, atypical bacterial and nonbacteraemic typical bacterial infection, respectively, and 58% (49 – 68%) for differentiation between bacterial and viral infection. PCT may be useful in identifying bacteraemia among children hospitalized with community-acquired pneumonia. IFN- α was uncommonly detected.